A wireless communication device, such as a phone or computer, propagates wireless signals over the air. To generate a wireless signal, the wireless communication device modulates a user data signal with a carrier signal to generate a corresponding Radio Frequency (RF) signal. The wireless communication device then amplifies the RF signal and drives an antenna with the high-power RF signal. Much of the battery power in the wireless communication device is consumed by the power amplifier that produces the high-power RF signal.
In the field of communications, transmit diversity refers to the redundant transmission of a user data signal. The redundant transmission may occur over separate paths and/or use separate transmitters. In a wireless communication device, transmit diversity entails the use of two power amplifiers to generate and transmit two high-power RF signals that each carry the same user data. Although transmit diversity consumes significant battery power, transmit diversity typically provides better bandwidth and range than a single-transmit approach without transmit diversity.
Some wireless communication devices include geographic location systems, such as Global Position Satellite (GPS) circuitry or radio triangulation circuitry. Wireless communication devices are also usually aware of the nearby base stations and their identifiers. In addition, wireless communication devices typically track their current battery charge and whether or not the battery is currently charging.
Overview
In a wireless communication device, a geographic location system determines a geographic location of the wireless communication device. A power monitoring system determines battery power status for the wireless communication device. A transmit diversity control system determines a transmit diversity instruction for the geographic location. The transmit diversity control system processes the transmit diversity instruction and the battery power status to select a transmit diversity mode (on/off). The transmit diversity control system controls a plurality of power amplifiers to implement the selected transmit diversity mode.